Backrest for a chair



FIG. 1 is a front perspective view of a backrest for a chair of the present invention;

FIG. 2 is a rear perspective view of the backrest for a chair;

FIG. 3 is an enlarged back view of the backrest for a chair;

FIG. 4 is an enlarged front view of the backrest for a chair;

FIG. 5 is an enlarged top view of the backrest for a chair;

FIG. 6 is an enlarged bottom view of the backrest for a chair; and,

FIG. 7 is an enlarged left side view of the backrest of a chair, with a right side view being a mirror image thereof.

The broken lines shown in the figures are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a backrest for a chair, as shown and described. 